This invention relates in general to four-wheeled draft vehicles or tow tractors such as are conventionally employed to haul vehicular trailers in highway travel, and more particularly, to a tractor having an interchangable connection arrangement for the tractor and trailer selectively providing either an articulated or a rigid unitary draft connection therebetween.
For certain applications such as, for example, the hauling of airport refueling tankers, it is desirable to employ a tractor-trailer rig arrangement in which the two units are rigidly interconnected or locked together so as to operate as a straight truck. The tractors commonly in use at present for hauling trailers are normally equipped with a so-called fifth-wheel coupling member to which a kingpin on the forward end of the trailer underframe is attached to provide an articulated draft connection between the tractor and trailer. Such fifth-wheel connection type tractors thus afford no way of using them in a straight truck application wherein the tractor chassis frame is locked in place to the trailer underframe to provide a rigid unitary interconnection therebetween. Likewise, and so far as known, there are no straight truck type tractor-trailer arrangements presently in use or known that provide any way for disconnecting or exchanging the tractor unit.